package com.hrbxlh.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**
* -------------------------------------------------------
* Copyright (c) 2017, 鑫联华信息科技股份有限公司
* All rights reserved.
* FileName：CaptchaUtil.java
* Description：验证码util类,负责验证码的生成及替换
* History：
* Date           Author               Desc
* 2016-5-7		     商莹                                           建立
* -------------------------------------------------------
*/

public final class CaptchaUtil{
	
    private CaptchaUtil(){}
    
    /*
     * 随机字符字典
     */
    private static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8',
        '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M',
        'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
    
    /*
     * 随机数
     */
    private static Random random = new Random();
    
    /*
     * 获取6位随机数
     */
    private static String getRandomString(){
        
    	StringBuffer buffer = new StringBuffer();
        for(int i = 0; i < 4; i++){
            buffer.append(CHARS[random.nextInt(CHARS.length)]);
        }
        return buffer.toString();
    }
    
    /*
     * 获取随机数颜色
     */
    private static Color getRandomColor(){
        return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
    }
    
    /*
     * 返回某颜色的反色
     */
    private static Color getReverseColor(Color c){
        return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());
    }
    
    public static void outputCaptcha(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

        response.setContentType("image/jpeg");
        String randomString = getRandomString();
        request.getSession(true).setAttribute("randomString", randomString);
        System.out.println("刚存就取"+request.getSession().getAttribute("randomString"));
        int width = 80;
        int height = 26;
        
        Color color = getRandomColor();
        Color reverse = getReverseColor(color);

        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bi.createGraphics();
        g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16));
        g.setColor(color);
        g.fillRect(0, 0, width, height);
        g.setColor(reverse);
        g.drawString(randomString, 18, 20);
        for (int i = 0, n = random.nextInt(100); i < n; i++){
            g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
        }
        
        // 转成JPEG格式
        ServletOutputStream out = response.getOutputStream();
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        encoder.encode(bi);
        out.flush();
    }
}